imapclient: add support for MULTIAPPEND

imapclient/append.go

@@ -54,3 +54,57 @@ func (cmd *AppendCommand) Close() error {
 func (cmd *AppendCommand) Wait() (*imap.AppendData, error) {
 	return &cmd.data, cmd.cmd.Wait()
 }
+
+// MultiAppend sends an APPEND command with multiple messages.
+//
+// The caller must call MultiAppendCommand.Close.
+//
+// This command requires support for the MULTIAPPEND extension.
+func (c *Client) MultiAppend(mailbox string) *MultiAppendCommand {
+	cmd := &MultiAppendCommand{}
+	cmd.enc = c.beginCommand("APPEND", cmd)
+	cmd.enc.SP().Mailbox(mailbox)
+	return cmd
+}
+
+// MultiAppendCommand is an APPEND command with multiple messages.
+type MultiAppendCommand struct {
+	cmd
+	enc *commandEncoder
+	wc  io.WriteCloser
+}
+
+// CreateMessage appends a new message.
+func (cmd *MultiAppendCommand) CreateMessage(size int64, options *imap.AppendOptions) io.Writer {
+	if cmd.wc != nil {
+		// TODO: handle error
+		cmd.wc.Close()
+		cmd.wc = nil
+	}
+
+	cmd.enc.SP()
+	if options != nil && len(options.Flags) > 0 {
+		cmd.enc.List(len(options.Flags), func(i int) {
+			cmd.enc.Flag(options.Flags[i])
+		}).SP()
+	}
+	if options != nil && !options.Time.IsZero() {
+		cmd.enc.String(options.Time.Format(internal.DateTimeLayout)).SP()
+	}
+	cmd.wc = cmd.enc.Literal(size)
+	return cmd.wc
+}
+
+// Close ends the APPEND command.
+func (cmd *MultiAppendCommand) Close() error {
+	err := cmd.wc.Close()
+	if cmd.enc != nil {
+		cmd.enc.end()
+		cmd.enc = nil
+	}
+	return err
+}
+
+func (cmd *MultiAppendCommand) Wait() error {
+	return cmd.cmd.Wait()
+}